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INTEGRATED POND AQUACULTURE IN LAKE VICTORIA WETLANDS

Anne A. van Dam, Rose C. Kaggwa, Julius Kipkemboi
Department of Environmental Resources
UNESCO-IHE Institute for Water Education
Delft, The Netherlands

van Dam, A.A., Kaggwa, R.C. & Kipkemboi, J. 2006. Integrated pond aquaculture in Lake Victoria wetlands. In M. Halwart & A.A. van Dam, eds. Integrated irrigation and aquaculture in West Africa: concepts, practices and potential, pp. 129–134. Rome, FAO. 181 pp.

Abstract

Wetlands are important for the livelihoods of millions of people. They provide food and income, support biodiversity and form a hydrological and ecological buffer between upland areas and water bodies. Population growth and the associated environmental degradation exert increasing pressure on wetlands. An example is the Lake Victoria region in East Africa, where human population growth, introduction of exotic fish species, overfishing and eutrophication have led to a deterioration of the wetland resources. For the riparian communities, this means a threat to their livelihoods as they depend on the wetland for food and income from fishing, seasonal agriculture and harvesting of wetland products. There is a need for integrated food production and waste processing technologies that enable communities to secure their livelihood without endangering the integrity of the natural resources. One such technology is integrated wetland pond aquaculture, or “fingerponds”. Ponds are dug from the landward edge of wetlands and extend like fingers into the swamp (hence the term “fingerponds”). Soil from the ponds is heaped between the ponds to form raised beds for crop cultivation. The ponds are stocked with fish through natural flooding in the rainy season. As the waters recede, the trapped fish are cultured using manure, crop and household wastes to fertilize the ponds and feed the fish. UNESCO-IHE and partners in Tanzania, Uganda, Kenya, Czech Republic and UK are currently involved in an EU-funded project to investigate the feasibility of this technology. Research focuses on the technical aspects, and on the socio-economic and environmental impacts of this technology. Also, options for integrating fingerponds with other wetland technology, such as the use of natural or constructed wetlands for wastewater treatment, need to be evaluated. Initial results of the research from Kenya and Uganda show that flooding can yield enough fish for stocking the ponds and that manuring of the ponds can increase their productivity.

Introduction

Wetlands are important for the livelihoods of millions of people. They provide food and income, support biodiversity and form a hydrological and ecological buffer between upland areas and water bodies. A definition given by the Ramsar Convention states that wetlands are “areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres”. In addition, wetlands “may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six metres at low tide lying within the wetlands”. This includes habitat types like rivers and lakes, coastal lagoons, mangroves, peatlands, and coral reefs, and also human-made wetlands such as fish and shrimp ponds, farm ponds, irrigated agricultural land (including ricefields), salt pans, reservoirs, gravel pits, sewage farms, and canals (Ramsar Info Pack, http: //www.ramsar.org/index_about_ramsar.htm).

Population growth and the associated environmental degradation exert increasing pressure on wetlands. An example is the Lake Victoria basin in East Africa with approximately 30 million people, where human population growth, introduction of exotic fish species, overfishing and increasing waste discharges (leading to eutrophication) have led to a deterioration of the wetland resources. For the riparian communities, this means a threat to their livelihoods as they depend on the wetland for food and income from fishing, seasonal agriculture and harvesting of wetland products. There is a need for integrated food production and waste processing technologies that enable communities to secure their livelihoods without endangering the integrity of the natural resources (Salafsky and Wollenberg, 2000).

Figure 1. Fingerpond setup.

In this paper, one technology which may contribute to sustainable wetland management is highlighted. This technology is integrated wetland pond aquaculture, or “fingerponds”. We explain the concept of fingerponds, and describe the current research efforts of UNESCO-IHE and its partners, together with some preliminary results from the first year of research (mainly 2002). The potential for further development and priority research issues are also discussed.

Fingerpond concept

Fingerponds are ponds dug from the landward edge of wetlands that extend like fingers into the swamp (hence the term “fingerponds”) (see Figure 1). Soil from the ponds can be heaped between the ponds to form raised beds for crop cultivation. The ponds are stocked with fish through natural flooding in the rainy season. As the waters recede, the trapped fish are cultured using manure, crop wastes and household wastes to fertilize the ponds and feed the fish. The water level in the ponds is maintained into the dry season by seepage from the adjacent wetland. The idea of fingerponds in the Lake Victoria region was described by Denny (1989; 1991) and Bugenyi (1991). It has developed from flood retreat farming and flood-based fishing practices found in many seasonally-flooded areas as the Sudd and Lake Chad. It is also similar to the many other seasonal aquaculture systems in other parts of the world, e.g. traditional coastal aquaculture systems like the tambak systems for milkfish production in Indonesia or the dambo ponds in southern Malawi.

The main features of fingerponds are: (1) water supply by natural flooding; (2) self-stocking through fish coming in with the flood water; (3) polyculture; (4) integration with crop production on the beds and with wastes and/or manures from household and livestock. Natural water supply and natural fish stocking in combination with waste inputs mean that the operating costs of these systems are kept low. The downside of this is that control over the operation is limited. Sites may remain flooded longer than expected, may flood unexpectedly during the culture season or may dry up sooner than expected, thus reducing the length of the culture period. The management of such systems and their economics are as yet unknown, hence the research project reported in this paper.

Collaborative research and training in wetland aquaculture

In 2001, a research project entitled “The dynamics and evaluation of fingerponds in East African freshwater wetlands” and funded by the European Union INCO-DEV program (the program that promotes scientific cooperation between EU member and developing countries) was started. In the project, three partners from Africa (Uganda, Kenya and Tanzania) and three from Europe (UK, Czech Republic, Netherlands) collaborate (see Table 1 for details of the partners). The objectives of the project are: (1) to establish criteria for optimal fish yields; (2) to assess the socio-economic benefits and evaluate trade-offs between fingerponds and other activities; (3) to develop practical fish production guidelines.

Table 1. Partners and work packages in the EU-INCO-DEV Fingerponds project ("The dynamics and evaluation of fingerponds in East African freshwater wetlands").

The research is carried out in six field locations, two in each of the African partner countries, where the local community participates in the project. During the first year of the project, four ponds measuring 8 Х 24 meter and with a depth of 2 m on the landward side and about 1 m towards the lake were constructed at each site. The local communities were involved in the choice of the sites and the construction of the ponds. For all sites, standardized protocols for ecological and hydrological monitoring and data collection were agreed and equipment (e.g., piezometers, evaporation pans) was installed. Here, we report some preliminary results from the sites in Kenya and Uganda (see Figure 2).

In Kenya, the study sites are located in Kusa (Nyanza province, Nyando district) at the mouth of the Nyando river and in Nyangera (Nyanza province, Bondo district) in the delta of the Yala river, both on the shores of Lake Victoria. A survey was carried out among the local community in both sites to document the use of the wetlands and their importance in the livelihoods of the communities. Papyrus harvesting, cattle grazing and seasonal agriculture were the main activities. Fish is an important part of people's diets and fishing is an important part-time activity. Papyrus (Cyperus papyrus) and Phragmites mauritianus Kunth. are important macrophytes: they are used for mats, in house construction, and as a fuel. Grasses and sedges (notably Digitaria scalarum; Cyperus involucratus) are also harvested from the wetlands. Seasonal agricultural crops are sugar cane, coco yam, arrow roots, bananas, rice and vegetables (spinach, kale, tomatoes, onions).

There are usually two flooding periods in this area, a major flood that occurred in May 2002 (Kusa) and from May–July 2002 (Nyangera), and a minor flood at the end of the year. These floods brought the water needed to fill the ponds and the fish needed for stocking. After the flood receded, a census of the fish population was done by pulling seine net through the ponds three times. In Kusa, about 800 fish per pond were caught in three of the ponds, and 56 fish in the fourth pond, or on average about 3 individuals per m² (Kipkemboi, 2003). After the census, the fish were re-distributed to achieve a uniform stocking density per pond. Species encountered were Oreochromis niloticus, O. variabilis, O. leucostictus, Clarias gariepinus, Aplocheilicthys sp., Ctenopoma murei, and Proptopterus aethiopicus. The majority of the fish (85–90%) were Oreochromis juveniles (< 5 cm). Further research at the Kenyan sites concentrates on the management of the ponds (nutrient enrichment using cattle manure), the economics of fingerponds and their role in the livelihoods system of the local communities, and the environmental impact of the ponds on the wetland ecosystem.

In Uganda, the study sites are located in Gaba wetland, 13 km south east of Kampala in the Inner Murchison Bay, and in Walukuba wetland in Jinja, near the Napolean gulf of Lake Victoria. The natural vegetation of these wetlands is dominated by Phragmites mauritanus, Cladium mariscus, Cyperus papyrus, Echinochloa pyramidalis and Typha domingensis (Kaggwa et al., 2001). Agricultural crops grown in the wetlands include coco yam, beans, maize, sweet potatoes, cassava, cabbages, sugar cane and rice. At both sites, flooding normally occurs once per year during the heavy rains in the period March–May. Pond soil analysis prior to flooding showed that the Gaba ponds contained 36–41% sand, 14–24% silt and 37–47% clay; in Walukuba, this was 28–31%, 40–45% ad 28–31%, respectively. Pond soils were alkaline (pH 7.6–9.1) and had organic matter content in the top 5 cm layer of 0.28–0.63% in Gaba and 0.65–1.1% in Walukuba (Kaggwa et al., 2005).

Figure 2. Location of fingerpond field sites in Uganda (1=Gaba, 2=Walukuba) and Kenya (3=Nyangera, 4=Kusa).

Ponds in Walukuba were still under construction in the first project year. In Gaba, three ponds were flooded and stocked naturally with fish. After 10 months of growth, a total of 1380, 364 and 620 fish were harvested in ponds 2, 3 and 4, respectively (pond 1 did not flood). In all ponds, tilapia (Oreochromis niloticus, O. leucostictus and O. variabilis) represented 93% or more of the individuals. Other species encountered were Haplochromis spp., Aplocheilicthys pumulis and Propopterus sp. Total fish weight from these three ponds was 16.3 kg, or 282 kg/ha. This was without any manure or feed input. Further research at the Ugandan sites concentrates on the management of the ponds, especially nutrient enrichment using chicken manure and the use of local plant materials (papyrus, Phragmites, bamboo and raffia) as substrates for periphyton.

People in the communities have expressed their doubts about the size of the fish in the ponds. They seem to expect big fish, like the ones they see landed for the export market from Lake Victoria. When they learn that it is unlikely that such big fish will ever be produced in fingerponds, they express disappointment. On the other hand, many people must be used to eating smaller fish from occasional fishing in the wetlands. To produce meaningful fish harvests in these ponds, technnical research should concentrate on two main topics: (1) pond fertilization strategies using locally available resources to increase pond productivity; and (2) fish harvesting strategies that optimize fish density and fish growth. With regard to the latter point, initial results from natural stocking show that differences in fish abundance after flood recession between neighbouring ponds can be substantial. Re-distribution of fish is then necessary. Also, initial densities can be quite high. Excess fish may have to be removed from the ponds. It is not clear whether there may be a market for these (generally small) fish, or whether implementation of fingerponds on a larger scale might constitute a threat to fish recruitment in the lake.

Options for further development and research needs

At this point, it is too early to draw firm conclusions about the technical and economic feasibility of fingerponds¹. Initial results show that it is possible to flood ponds naturally and achieve self-stocking with fish. Baseline fish yields based on natural stocking of the ponds without additional inputs will be established, and there seem to be no major soil or water quality constraints to culturing fish. A wide range of organic materials for fertilizing ponds are available, ranging from different types of manure to wetland grasses and crop wastes. Technically, extensive to semi-intensive pond management will be possible. There is a demand for fish among the local population, since most fish from the Lake Victoria capture fisheries is going to export markets or to the fishmeal industry (Okeyo-Owuor, 1999).

¹ Between the presentation of this paper and its publication in this volume, additional reports about the Fingerponds project have been published (e.g., Bailey et al., 2005; Kaggwa et al., 2005; Pokorny et al., 2005).

One point that needs more research is the context for development of aquaculture in the Lake Victoria basin. Apart from fishing, communities in this area are involved mainly in harvesting and processing of natural products from the wetlands like papyrus. Agriculture is practiced seasonally by clearing part of the wetland and growing the crops on the residual moisture without much fertilization. In Kusa, clearing of the land is done communally, but subsequent management of the plots is done individually (J. Kipkemboi, personal communication, 2003). It is not clear how fishponds fit into this system, e.g. in terms of ownership. The initial investment for pond construction is considerable, and it is not clear yet how much maintenance is needed for ponds after a year of flooding and drying up. Adoption of this system will probably depend to a large extent on the trade-off between the benefits of fingerponds and other wetland or off-farm activities. This issue will be addressed in our research by bio-economic modelling of the wetland agro-ecosystem.

The partners in the Fingerpond project are considering a continued collaboration in this area after the current project ends in 2005. There are ideas about integrating several wetland wise-use technologies, implementing participatory field trials with communities in the Lake Victoria basin and doing research on the links between technology development, adoption and policy and decision-making for wetland management. Examples of these other technologies are constructed and natural wetlands for wastewater treatment (Kansiime and Nalubega, 1999; Okurut, 2000) and dry sanitation techniques.

Acknowledgements

The Fingerponds project described here is funded by the EU INCO-DEV program, contract no. ICA4–CT–2001–10037. The PhD-research projects of Julius Kipkemboi and Rose Kaggwa are partially supported by grants from the Netherlands Fellowship Program. We thank Patrick Denny for his comments and suggestions. The Fingerponds project collaborates with several other projects, organizations and institutions in the Lake Victoria region. Here, we would like to mention the support of the National Water and Sewerage Corporation, Uganda and the RELMA-SIDA project, Kenya.

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